Indo-Australian Plate Research Articles

Comparative Study of Internal Force between Dynamic Method and Equivalent Static Methods in Lecture Buildings in Yogyakarta Based on Earthquake Indonesian National Standard (SNI 1726-2019)

Earthquakes are events of the movement of the earth due to the sudden release of energy in the earth which is marked by the breaking of the rock layers in the earth’s crust. Indonesia is located in an earthquake-prone area where three tectonic plates meet, namely the Indo-Australian plate, the Eurasian plate and the Pacific plate. Realizing the threat of an earthquake that could occur at any time, the Indonesian government took the initiative to take measures to prevent the risk of damage to infrastructure that could occur due to an earthquake. This paper presents an analysis of the earthquake resistance of a lecture building at an educational institution in the city of Yogyakarta with the equivalent static method and the dynamic response spectrum method. The purpose of this paper is to provide an overview of whether construction projects that have been implemented using SNI 1726-2012 are analyzed and compared with the latest standards, namely SNI 1726-2019, whether the building construction still meets earthquake resistance. The results of the comparative analysis of the equivalent static method and the dynamic response spectrum method show that the building under study does not meet the strength and resistance to earthquakes based on SNI 1726-2019, so it is necessary to strengthen the structure of the building under study.

Simulation of Oil Spill Pollution due to Tsunami in Cilacap, Central Java, Indonesia

Cilacap, located on the south coast of Java Island, is an “oil and gas city”. Cilacap has many oil refineries, storage, and loading & unloading facilities. However, these facilities’ existence is threatened by the potential for earthquakes and tsunami in Cilacap because Cilacap is very close to the Eurasia and Indo-Australian plates’ subduction zone. The earthquake and tsunami waves can damage these facilities and cause secondary disasters, namely oil spill pollution. The first step to anticipate is to predict the direction and distribution of the oil spill due to tsunami through simulation and numerical modeling. This simulation and modeling used the TUNAMI model, hydrodynamic model, and spill analysis model based on the worst-case scenario (Mw 9.0 earthquake). This study simulates and models the oil spill in the west and east monsoons. Based on this simulation and modeling result, we know that the direction and distribution of the oil spill in the west and east monsoons are relatively the same and move more dominantly in the current direction. The spread of the oil spill caused by the tsunami was faster than the oil spill in general. Some of the oil spills spread inland more than 1 km north of the Teluk Penyu coast. The authors expect this study’s results can be used as material for preparing of contingency plans for handling oil spills to minimize negative impacts.

Shallow subsurface velocity model at Simeulue Island, Indonesia inferred from ambient vibration records

Simeulue Island is located in the forearc west of Sumatra Island. Due to the subduction process of the Indo-Australian plate beneath the Eurasian plate, high seismic activities occur around Simeulue Island. A temporary seismic network was installed on the island from December 2005 to March 2006 to study seismicity around this region. From previous studies, using ambient vibration records, it is possible to extract a site amplification of sediment on the top of a bedrock, which gives influence on the seismic signal. In addition to the site amplification, it is also possible to determine information of the velocity model on the shallow subsurface. In this preliminary study, we applied horizontal to vertical time frequency analysis (HVTFA) to obtain ellipticity from recorded vibration from three temporary seismometers. An inversion was applied to the computed Rayleigh ellipticity to obtain the best fit subsurface velocity model.

ANALISIS KOMPOSISI UNSUR DAN JENIS MINERAL BATUAN GUNUNGAPI SOPUTAN MENGGUNAKAN SEM-EDX DAN FTIR

Volcanoes are mountains that are formed as a result of eruption material accumulating around the center of an eruption or a mountain formed from a magma eruption. Volcanoes are only found in certain places, namely in the mid-ocean ridge, at the point where two plates of the Earth's crust meet, and at hot spots on the earth where magma is released, on continents and in oceans. Indonesia is a country with active volcanoes formed due to subduction zones between three tectonic plates, namely the Eurasian plate, the Indo-Australian plate and the Pacific plate. The location of the research was carried out in the Soputan Volcano Area, by taking two samples, namely two different rock types in the study area. This study aims to determine the elemental composition of the rock and rock mineral types in Soputan Volcano. Using SEM-EDX and FTIR. The results of the research on sample 1 of the EDX device were Bromine, Silica, Tungstate, Gold, Molybdenum, Calcium, Iron, Iterbium, Lutetium. And in sample 2 of the EDX tool, namely Aluminum, Silica, Iron, and Cobalt, and the results of field research that has been conducted using SEM-EDX and FTIR, it can be concluded that: The elemental composition of volcanic rock in Soputan volcano has Br, Si elements. , W, Au, Mo, Ca, Fe, Yb, Lu, Al, Co. As well as the type of rock minerals, basalt in sample 1 and sample 2 is andesite.

Interpretasi Tingkat Kekerasan Batuan Bawah Permukaan di Daerah Rawan Gempa Bumi Kota Bengkulu

<p class="AbstractText">Bengkulu City is located in the subduction zone of the Indo-Australian and Eurasian plates, so it is prone to earthquake. To anticipate the impact of earthquake, disaster mitigation can be carried out, one of which is a study of the level of rock hardness in the area. This study aims to determine the level of rock hardness based on seismic wave velocity in several rock formations and to determine which rock formations have the potential to cause vulnerability to earthquakes. Field data acquisition uses the seismic refraction method with time-term inversion technique. The data obtained in the field are processed to obtain a 2-D cross-section of the subsurface seismic wave velocity values. The study results show that the level of rock hardness depends on the type of rock formation. The Andesite Rock Formation Unit (Tpan) has the highest level of hardness, while the transitional area between the Alluvium Rock Formation Unit (Qa) and the Swamp Sedimentary Rock Formation Unit (Qs) has the lowest level of hardness.</p>

Efektivitas Penerapan Media Komik Tanggap Bencana Terhadap Pengetahuan Kesiapsiagan Gempa Bumi di SMP Negeri 2 Pleret

Introduction: Indonesia is at a meeting between the Indo-Australian plate, the Eurasian plate and the Pacificplate. This plate has an influence in a disaster, one of which is an earthquake. Since the 1800s, the Special Regionof Yogyakarta has occurred five times a tectonic earthquake with a magnitude above 6 on the Richter scale.Objectives: Knowing the effectiveness of the implementation of disaster response comic media on knowledge ofearthquake disaster preparedness in class VII students in Pleret 2 Public Middle School.Methods: The type of quantitative research is the quasi experimental method, and the design is Nonequivalentwith control group. The study was conducted at Pleret 2 Public Middle School in May with a total sample of 68,measuring knowledge of disaster preparedness using a questionnaire. Data analysis using the Wilcoxon test todetermine the difference in pretest-posttest and Mann Whitney to determine the effectiveness of the treatmentgroup.Results: The results of the Wilcoxon analysis using comic media were 0,000 (p <0.05) indicating that there weredifferences before and after using comic media. The results of the Wilcoxon analysis in the control group were0.065 (p> 0.05) indicating that there was no difference before and after using the control group. The results ofMann Whitney analysis (0,000 <0,05) showed that there was effectiveness in using treatment groups.Conclusions: There is effectiveness in the implementation of disaster response comics media on knowledge ofearthquake disaster preparedness in class VII students in Pleret 2 Middle School.

Tectonic constraints on formation and evolution of microplates in the Indian and Pacific Oceans: reviews and statistical inferences

Oceanic plates are growing through narrow boundaries, such as mid-ocean ridges and transform faults. However, the discovery of diffuse plate boundary suggests another type of plate boundary that accommodates difference in plate motion via internal deformation. Along the Central and Southeast Indian ridges, for example, the Capricorn and Macquarie microplates exhibit widespread diffuse boundaries and hence divide the Indo-Australian Plate further into the Indian, Australian, Capricorn, and Macquarie plates. As for microplates distributed along the East Pacific Rise and Pacific-Antarctic Ridge in the Pacific Ocean, however, the typical plate boundaries surrounding the given microplate are distinctly established. Global plate reorganization involving the changes in plate motion or in spreading direction can be accommodated by forming a microplate through ridge extinction, ridge propagation, and pseudofault formation. However, relations between these tectonic processes have not been quantitatively assessed. In particular, we aim to examine tectonic constrains on the formation processes of microplates with diffuse plate boundary. In this study, we compare plate size, plate age, full-spreading rates, thermal structures, total rotation, and rotation rate for the 9 microplates including extinct plates (i.e., Capricorn, Macquarie, and Mammerickx* microplates in the Indian and Southern Oceans; Galapagos, Easter, Juan Fernandez, Bauer*, Friday*, and Selkirk* microplates in the Pacific Ocean; extinct plates are denoted with asterisks). From this comparison, we find that the microplate formation would require certain tectonic conditions (e.g., full-spreading rates faster than 70–80 mm/yr and rotation rates faster than 5–6°/m.y.) to evolve into an independent and rigid plate with respect to the neighboring plates. If the conditions are not met, the same tectonic reorganization would result in a microplate with diffuse plate boundaries.

Geomorphology and Neotectonics of Southwestern Crimea

Abstract—The area of southwestern Crimea includes the ending of the Crimean Mountains that arose during the neotectonic activation at the place of the Cretaceous–Paleogene denudation plain and the adjacent shallow-water carbonate sedimentation basin. The Crimean Mountains are one of the links of the Alpine–Himalayan orogenic belt formed during the collision of the Eurasian, African, and Indo–Australian plates. Their area includes late Cenozoic marine terraces of the complete Mediterranean series and a staircase of Neogene, Paleogene and Cretaceous planation surfaces over them. The planation surfaces of different ages resulted from the successive lowering of the World Ocean level. Their subsequent deformations make it possible to outline the area of the neotectonic uplifting and determine its parameters. The main mechanism of the neotectonic activation was the thrust of the East Black Sea microplate under the Scythian one and the formation of a ramp fold structure. The amplitude of the neotectonic uplifting of southwestern Crimea for the past 2 Myr varies from 0 to 800 m, i.e., is up to 0.04 mm/year. The recent neotectonic structure of the area is formed by the northern flank of the ramp fold; it is a monocline of NW dip consisting of “keys” of NW strike separated by the latest faults with vertical displacements of 10 to 120 m. The uplifting of the area and the lowering of the World Ocean level led to a widespread of denudation surfaces. Their good preservation makes it possible to refine the sequence of neotectonic events, whose first pulses reached the study area in the Oligocene, and the main activation phase began in the Pliocene.

Fluvial response to active tectonics: analysis of DEM-derived longitudinal profiles in the Rangit River Basin, Eastern Himalayas, India

The Himalayan Mountain Range has originated from the ongoing collision of the Eurasian and the Indo-Australian plates since the Paleogene. It is widely accepted that this tectonically-driven uplift is still continuing, as reflected by a large number of earthquakes in the area. Apart from the sub-surface and geophysical signatures, the surficial geomorphic markers deserve due attention. Fluvial systems, which preserve the evidence of the past and present tectonic perturbations on the surface, have often been investigated to assess the imprints of uplift in a region. Sensitive to long-term tectonic, structural and climatic regimes, the general forms of the longitudinal profile and its derivatives have been analysed across the globe for determining the varying roles of tectonics, litho-structure and climate. This article assesses the degree of tectonic and lithological control on the drainage network of the Rangit Basin in the Eastern Himalayas. One of the important characteristics of the studied basin is that the Main Central Thrust (MCT), which is located between the Greater Himalayas and the Lesser Himalayas, divides the basin into two distinct domains. Longitudinal profiles and their derivatives of 16 major tributaries of the Rangit River were extracted from the ALOS–PALSAR DEM and analysed. The controls on this Himalayan river were evaluated based on investigations of longitudinal profile shapes, stream gradient (SL) indices, longitudinal profile concavities and steepness. Prominent drainage anomalies such as above-grade conditions, exponential and linear fitting of longitudinal profiles, elevated values of SL indices, barbed drainage, over-steepened stream segments and fluvial hanging valleys imply rapid erosion rates in the basin. This is noticeable particularly in the lower domain of the Rangit Basin, especially in the areas located downstream of the MCT. A comparison of steep segments with the geological and lineament maps reveals that many of these anomalies are lineament-controlled. Furthermore, a large number of such features do not conform to lithological intersections, suggesting a possible tectonic factor behind the occurrence of such anomalies.

Mid-Miocene volcanic migration in the westernmost Sunda arc induced by India-Eurasia collision

AbstractThe migration of arc magmatism that is a fundamental aspect of plate tectonics may reflect the complex interaction between subduction zone processes and regional tectonics. Here we report new observations on volcanic migration from northwestern Sumatra, in the westernmost Sunda arc, characterized by an oblique convergent boundary between the Indo-Australian and Eurasian plates. Our study indicates that in northwestern Sumatra, volcanism ceased at 15–10 Ma on the southern coast and reignited to form a suite of active volcanoes that erupt exclusively to the north of the trench-parallel Sumatran fault. Younger volcanic rocks from the north are markedly more enriched in K2O and other highly incompatible elements, delineating a geochemical variation over space and time similar to that in Java and reflecting an increase in the Benioff zone depth. We relate this mid-Miocene volcanic migration in northwestern Sumatra to the far-field effect of propagating extrusion tectonics driven by the India-Eurasia collision. The extrusion caused regional deformation southward through Myanmar to northwestern Sumatra and thus transformed the oblique subduction into a dextral motion–governed plate boundary. This tectonic transformation, associated with opening of the Andaman Sea, is suggested to be responsible for the volcanic migration in northwestern Sumatra.

Mapping of Tsunami Disaster Mitigation Evacuation Routes of the Movement of the Sunda Subduction Megathrust (Case Study: Coastal Analysis of Southern Garut Regency)

Potential disaster due to the movement of the subduction zone between the Eurasian Plate and the Indo-Australian plate, extending from the west of Sumatra to the south of Java, Bali, and Nusa Tenggara. This subduction zone is called the Sunda subduction arc. It has several segments. The Java segment has a lower seismic magnitude and frequency. Megathrust is a shallow part of the subduction lane which has a shallow dive angle, so the impact on the southern part of Garut Regency has the potential for earthquake and tsunami disaster, has been analyzed spatially and geoprocessing with geographic information systems, plotting 149 earthquake points from 1958 to 1920, planning evacuation routes for earthquake and tsunami disaster mitigation, as well as measuring coordinates, height, slope, and width between the coast and settlements, tourist attractions, main roads south of West Java, and evaluation of existing evacuation routes so that the community has an evacuation route adequate and safe.

Inherited lithospheric structures control arc-continent collisional heterogeneity

Abstract From west to east along the Sunda-Banda arc, convergence of the Indo-Australian plate transitions from subduction of oceanic lithosphere to arc-continent collision. This region of eastern Indonesia and Timor-Leste provides an opportunity for unraveling the processes that occur during collision between a continent and a volcanic arc, and it can be viewed as the temporal transition of this process along strike. We collected a range of complementary geological and geophysical data to place constraints on the geometry and history of arc-continent collision. Utilizing ∼4 yr of new broadband seismic data, we imaged the structure of the crust through the uppermost mantle. Ambient noise tomography shows velocity anomalies along strike and across the arc that are attributed to the inherited structure of the incoming and colliding Australian plate. The pattern of anomalies at depth resembles the system of salients and embayments that is present offshore western Australia, which formed during rifting of east Gondwana. Previously identified changes in geochemistry of volcanics from Pb isotope anomalies from the inner arc islands correlate with newly identified velocity structures representing the underthrusted and subducted Indo-Australian plate. Reconstruction of uplift from river profiles from the outer arc islands suggests rapid uplift at the ends of the islands of Timor and western Sumba, which coincide with the edges of the volcanic-margin protrusions as inferred from the tomography. These findings suggest that the tectonic evolution of this region is defined by inherited structure of the Gondwana rifted continental margin of the incoming plate. Therefore, the initial template of plate structure controls orogenesis.

More accurate study of seismicity effect on Sumatra-Fault for liquefaction potential in Banda Aceh by using cyclic loading mobility data

Banda Aceh is a prone city, predictions from earthquake experts with a potential for a tsunami in the return period of 500 years there will still be a large earthquake that threatens development in Aceh, especially Banda Aceh. A great earthquake has occurred in Aceh on December 26, 2004, which destroyed government infrastructures and property and human life in Banda Aceh. The high number of casualties during the natural disaster occurred due to low government preparedness and public understanding of earthquake disasters caused by several earthquake sources surrounding the city of Banda Aceh, such as; Aceh-Sumatra great fault, the subduction of the Indo-Australian plate with the Euro Asia plate which move side by side along the side of Aceh province - Andaman Island. This research will provide important information regarding the orientation of the depth of the strong layer and the distribution (horizon) of the subsoil of the city surface in several densely populated zones and surrounded areas. The study method was carried out by using a cross-section of the sub-surface of the earth’s plate from the coast - transition - land using Surfer software. Quantitative and qualitative analysis results obtained 3D image surface sand shading relief; soft layers, moderately layers and hard layers, each of which the thickness and depth of the soil was used to perform an analysis of the phenomenon of liquefaction potential; soft layers less than 10 kg/cm2 thickness 0.2-3.6 m depth, moderately layers 10-50 kg/cm2 thick 1.0 -7.0 m depth 1.2-10.6 m, hard layers > 120 kg/cm2 thickness 2.0-18.6 m depth 5.0-46.8 m, respectively.

Updated Segmentation Model and Cummulative Offset Measurement of the Aceh Segment of the Sumatran Fault System in West Sumatra, Indonesia

Sumatran fault in western Indonesia is one of the largest strike-slip fault in the world. The fault was formed as a result of the slip partitioning of the oblique convergence between the Indo-Australian and Eurasian plate along the Sunda trench. The right-lateral movement of the fault is accomodated by 19 fault segments that dissects the entire Sumatra island. We study the Aceh fault segment, which is located at the northernmost parts of the fault. The Aceh fault segment spans 250 km long passing through three districts: West Aceh, Pidie Jaya, and Aceh Besar and is affecting a total of ~546.143 population in the area. The current segmentation model assumes that Aceh fault segment acts as a single fault segment, which would generate closer to a M8 earthquake. This estimation is inconsistent with the ~M6-7 historical earthquake data. We conduct a detailed active fault mapping using the ~8 m resolution digital elevation model of DEMNAS and the sub-m DEM data from UAV-based photogrammetry to resolve the segmentation model of this fault. Our study indicate that the Aceh fault segment can be divided into 8 subsegments: Beutong, Kuala Tripa, Geumpang, Mane, Tangse, Jantho, Indrapuri, and Pulo Aceh. The fault kinematics identified in the field is consistent with right-lateral faulting. We measured cumulative displacement of geomorphic features (channels and ridges) ranging from 12.7 to 1931 m at some area. Findings of our study provide better estimation of the fault geometry and the maximum magnitude of potential earthquake along the Aceh fault segment as well as recommendation of prospective sliprate study sites. These informations are important for the development of seismic hazard analysis of the area.

Formation of crystal-rich, mixed, intermediate lavas at Pouakai Volcano and the evolution of the Taranaki volcanic lineament, western North Island, New Zealand

Over the past ~2 Ma, volcanic activity in the western North Island of New Zealand has been focused along the NW to SE-younging Taranaki volcanic lineament (TVL). Geophysical imaging of the convergent boundary between the Pacific and Indo-Australian plates shows that the subducted slab lies at least ~200 km below the present TVL and the <200 ka andesitic Mt. Taranaki. Pouakai is the second youngest (~0.25 Ma) volcanic edifice of the TVL and lies immediately NW of Mt. Taranaki. It is deeply eroded with limited exposure, but it has been sampled by a major collapse event that generated the 0.21–0.24 Ma Maitahi debris avalanche deposit. The Pouakai lavas sampled by the Maitahi deposit are medium-K, pyroxene-bearing basalts and amphibole- and pyroxene- bearing basaltic andesites and andesites. Plagioclase, clinopyroxene and amphibole are the dominant phenocryst phases. Olivine and orthopyroxene are rare. Compared to younger Mt. Taranaki lavas, the Pouakai volcanic rocks have lower K, P, Ba, Rb, Sr and Zr and higher Sc and V abundances, and they define subtly different trends on TiO2, MgO and K2O versus SiO2 variation diagrams. Most Pouakai eruptives are similar to the older ring plain debris avalanche deposits of Mt. Taranaki, but Pouakai summit lavas are compositionally similar to younger Mt. Taranaki eruptives. For the Pouakai sample suite, the geochemical trends and patterns are broadly consistent with control by fractional crystallisation (FC), or assimilation fractional crystallisation (AFC). However, textural and geochemical evidence indicates that the rocks are not representative of simple magmas related by a common liquid line of descent. Pouakai basaltic andesites and andesites are highly porphyritic and phenocrysts show complex zoning and disequilibrium reaction textures. Mg# [mol. MgO/(MgO + FeO)] of amphibole and clinopyroxene compositions vary beyond the range expected if the minerals had equilibrated with melts having bulk whole rock compositions. Furthermore, geothermobarometry based on amphibole and pyroxene compositions indicates that mafic phenocrysts in all rock types, as well as in individual samples, equilibrated with comparatively felsic melts over a wide range of pressures. Therefore, each lava sample represents a mixed magma, comprising felsic melts derived from a range of crustal and mantle sources hosting a complex, polybaric phenocryst assemblage. The whole rock compositions were derived through varying degrees of bulk fractionation of phenocryst phases with net removal of amphibole and clinopyroxene and consequent concentration of plagioclase phenocrysts.

Consumed tectonic plates in Southeast Asia: Markers from the Mesozoic to early Cenozoic stratigraphic units in the northern and central Philippines

Tectonic reconstruction models of Southeast Asia all invoke in the early Cenozoic the collision of Mesozoic oceanic plates, which have been fragmented, consumed along subduction zones or emplaced onto the overriding plate. However, with marked variations in these models, we reinvestigate the tectonic evolutionary landscape of Southeast Asia through the lens of Philippine geology. In particular, we present revisions to the more recent models by adopting the unique approach of integrating data that we have gathered for the past 17 years from the Upper Mesozoic to Lower Cenozoic stratigraphic formations in northern and central Philippines. These formations, which resulted mainly from submarine mass transport processes, evolved in response to early arc-related processes of oblique subduction, frontal wedge deformation, terrane accretion and strike slip faulting. Additional key constraints for the revisions include: (1) the timing of early Cenozoic magmatism in eastern Luzon; (2) the spatial distribution of the Upper Mesozoic to Lower Cenozoic sedimentary formations with respect to other key features (e.g. distribution of Mesozoic ophiolite fragment and continent-derived rocks) in the Philippine arc; (3) the paleolatitudinal position of Luzon and surrounding regions and; (4) the movement of the surrounding plates since the Late Mesozoic.In revising previous models, a subduction zone (proto-East Luzon Trough) separating Benham Plateau and the Philippine arc was placed to explain the spatial distribution of Eocene arc-related formational units and Mesozoic ophiolite materials comprising the accretionary complex east of Luzon at ~40 Ma period. During this time, Luzon was modeled at the southern margin of the East Asia Sea or the proto-Philippine Sea Plate. Mesozoic ophiolitic complexes that line the eastern Philippine arc as well as the ophiolitic and pelagic limestone and chert fragments included in the arc-derived, Eocene formations in Luzon could very well be traces of the now consumed East Asia Sea-proto-Philippine Sea Plate. Within the same period, we modified the Palawan Microcontinental Block (PCB), positioned at the trailing edge of the proto-South China Sea to include the whole Mindoro island and the Romblon Island Group in Central Philippines. Pieces of the consumed Izanagi Plate, the proto-South China Sea and continental-derived sediments from Asia mainland are reflected in the Mesozoic metamorphic rocks and the Eocene sedimentary formation in western Mindoro. Finally, we model Cebu, Bohol and Negros islands in Central Philippines as being at the leading oceanic edge of the Indo-Australian Plate during the early Cenozoic. With the northward movement of the Indo-Australian plate and the trench roll back of the southern margins of the Philippine Sea Plate, the accretion of the Cretaceous arc-related rocks of Cebu, Bohol and Negros onto the Philippine arc by the end of Eocene or early Oligocene becomes a possibility.

Collaborative Governace in Post Earthquake Disaster Management on The Western Island of Java

The geographical conditions of Indonesia which are on the Pacific Ring of Fire and are crossed by three world plates, the Eurasian plate, the Indo-Australian plate and the Pacific plate make Indonesia the most disaster-prone country, especially earthquakes. The large number of population in Indonesia contributes to the risk of life and social loss, physical loss, and economic loss. Based on this, the government seems to need more attention to disaster management efforts, which are multidimensional. On the other hand, disaster management in Indonesia have not yet become a national strategic issue and development goals so that resulting in disaster management in Indonesia are still not optimal due to the collaborative management processes that are not comprehensive and sustainable between the various levels of actors involved.The purpose of this study is to analyze collaborative governance in the prevention of earthquake reconstruction rehabilitation in the Western Island of Java. This study uses a post positivism approach with qualitative research methods through in-depth interviews and documentation studies.The results of this study indicate that it is needed: the objectives in post earthquake disaste management must consider providing solutions that can reach ordinary people, community independence and participation, human resources, technology, finance and legal as well as derivative rules, leader support, and collaboration between governments, non-governmental institutions, private sector, donor agencies, international agencies, universities and the community

Analysis of Remote Sensing, Gravity, and Magnetotelluric Data on Geothermal Fields in Ogan Komering Ulu (OKU) District, South Sumatra

Geothermal energy is a clean alternative energy resource. Southern Ogan Komering Ulu (OKU), South Sumatera, is a geothermal prospect area because of the interaction between the Eurasian and Indo-Australian tectonic plates. It causes geological structures growth and the activity of volcanism in the area. Based on geological data, geothermal in southern OKU is indicated by the existence of 40–93 ºC temperature hot springs. Geological data based on remote sensing methods can determine the lineament. Geophysical data with gravity and magnetotelluric can identify the type of rock and the subsurface geological structure based on rock density and resistivity. Based on geological and gravity data indicates the presence of geological formations lead northwest-southeast, which is estimated as the geothermal fluid pathway with the suitability to the location of hot springs. The magnetotelluric data shows the geothermal reservoir rocks (clastic sedimentary rock) located at (-500)–(-2.500) meters depth with 30–200 Ωm resistivity. DOI: http://dx.doi.org/10.17977/um024v5i12020p022

Analisis Likuefaksi Berdasarkan Data CPT Untuk Perancangan Pondasi Di Pesisir Pantai Kabupaten Kulon Progo DIY

Yogyakarta Special Region (DIY) is an area that has a high level of seismic activity in Indonesia. This is due to various local faults near the land and its location adjacent to the subduction of the Indo-Australian and Eurasian plates. The proposed new airport is located on the coast in Kulon Progo Regency DIY. The location is dominated by the sands layer and it has high ground water levels which indicate the high potential of liquefaction. The site classes of the coast in Kulon Progo Regency is medium category (SD). Liquefaction analysis using the PGAM value of 0.4 g. Liquefaction has the potential to occur in soil layers 0 - 6 meters. The analysis shows for eartquake of ≥ 6.3 Mw has a very high category of liquefaction. The analysis results has LPI ≥ 29.30 for ground water conditions at the surface, and LPI ≥ 15.32 for ground water conditions in depths of 3 meters. Estimated soil settlements of 19.7 cm for magnitude of 8.1 Mw with ground water conditions at the surface. The use of shallow foundations at soil depths of 0-6 meters is not recommended, unless a soil improvement method is used to eliminate the potential for liquefaction.

Analisis Pengaruh Gempa Tektonik 10 Juli 2013 Terhadap Perubahan Koordinat Stasiun Pantau Segmen Mentawai

Mentawai Segment is located in Mentawai Islands, Sumatra, Indonesia. This segment is a subduction zone between Indo-Australian plate and Eurasian plate. This subduction zone can lead to high potential of tectonic earthquake in Mentawai Segment. The high potential of tectonic earthquake has negative impact for the community, so it is necessary to monitor the risk of tectonic earthquake in Mentawai Segment. This monitoring can be done by using GPS data of monitoring station that spread in Mentawai Segment. Therefore, this research aims to analyze the effect of tectonic earthquake on the coordinate change of Mentawai Segment, so that it can reduce the risk of negative impact of tectonic earthquake in Mentawai Segment. This research use observation data of 10 continuous GPS monitoring station (Sumatran GPS Data Array / SuGAr) in Mentawai Segment. Day of observation data was day of year (doy) at the time of tectonic earthquake occurence on July 10, 2013. Data processing used GAMIT / GLOBK software. The results of this research indicate that the tectonic earthquake (July 10, 2013) affected coordinates changes of the SuGAr station significantly two hours after the tectonic earthquake occurred.